There was a time, four or five decades ago, when financing, building and maintaining California’s immense highway network was considered to be the Capitol’s most important work.

No more.

Highways have slipped below the political radar, even though Californians rack up more than 300 billion miles of automotive travel each year and even though the highways suffer from severe deficiencies that would, the California Transportation Commission says, cost $700 billion over the next decade to erase, several times what current revenue would produce.

As noted in this space previously, an ideological disdain for highways among liberals, combined with an equally fierce dislike of taxes among conservatives, has been a recipe for political neglect.

California’s vehicular travel has doubled during the last 30 years, but fuel consumption has risen by only one-third – good news overall but bad news for our battered highways.

A long-standing tax system based on fuel volume has become obsolete as autos have become more fuel-efficient.

A study by the University of Southern California estimates that with adjustment for inflation, the state’s gas tax is worth much less than 50 percent of what it was in 1970, even with some rate increases during the period.

Basing road revenue on fuel gallonage, or even prices, is no longer realistic, and we should shift to mileage-based financing. It’s kicked around transportation circles for decades, but is gaining new traction among highway advocates.

The state Senate has approved a bill by Sen. Mark DeSaulnier, D-Concord, which would, as recently amended, create a “Mileage-Based Fee Task Force” within the California Transportation Commission to recommend a pilot project.

As passed by the Senate, Senate Bill 1077 would have ordered the California Transportation Agency to develop the pilot program, but the amended version adopts a more circuitous process.

The USC study said that a mileage fee of 2.1 cents per mile could completely replace the gas tax, and while it could take many forms, all raise questions of privacy. If travel is to be monitored and taxed, then how can the data be collected without a governmental Big Brother knowing where motorists are driving?

One big aspect of the proposed pilot project, therefore, will be to devise ways to protect personal privacy, and it’s not impossible. Oregon has devised a fee system that passes muster with the American Civil Liberties Union.

SB 1077 is just a baby step, and given the underlying political divisions, it may lead nowhere, even if the Assembly approves the bill. But it’s a start. Highways are not improving with age.